Com os crescentes movimentos ecolÃgicos em todo o mundo, onde o objetivo principal visa conscientizar e estimular a populaÃÃo mundial a poupar os recursos naturais, aliado a necessidade de se desviar os resÃduos aterrados (sanitÃrios ou industriais), de forma a reduzir os problemas ambientais e de saÃde pÃblica, decorrentes da disposiÃÃo inadequada de resÃduos sÃlidos, surgem os incentivos a reciclagem de materiais, bem como o desenvolvimento de materiais biodegradÃveis. Diante deste contexto, os materiais compÃsitos reforÃados com fibras naturais ganham destaque no meio cientÃfico. No entanto, seu uso ainda à tido com desconfianÃa, devido ao pouco ou nenhum conhecimento desses promissores materiais. Perante essa problemÃtica, surgiu a proposta deste trabalho de carÃter investigativo, em que foi pesquisado e desenvolvido um compÃsito totalmente reciclado, de matriz termoplÃstica (PVC reciclado) reforÃado, com fibras obtidas da casca de cocos verdes descartados. Para esse objetivo foram utilizadas diversas ferramentas de caracterizaÃÃo fÃsica, quÃmica, tÃrmica e mecÃnica, sendo os valores dos campos de deformaÃÃo obtidos pela CorrelaÃÃo de Imagem Digital (CID), comparando a imagem do corpo nÃo deformado com imagens do corpo deformado. E finalmente, avaliou-se os processos de danificaÃÃo do compÃsito, atravÃs da caracterizaÃÃo experimental da evoluÃÃo do dano isotrÃpico pelos mÃtodosda variaÃÃo do MÃdulo de Elasticidade efetivo (ensaio de traÃÃo com carga e descarga) e pelo Ãndice de Tsai-Wu com os parÃmetros constitutivos da funÃÃo tangente hiperbÃlica, onde os valores encontrados, em ambos os mÃtodos, mantiveram-se dentro da faixa esperada para compÃsitos, 0,20 â 0,50. / With increasing the ecological movements around the world, whose the main objective aims to raise awareness and encourage the world's population to save natural resources, coupled with the need to divert grounded waste (sanitary or industrial) in order to reduce environmental problems and public health, arising f rom the improper disposal of solid waste, emerge incentives for recy cling, and the development of biodegradable materials. Given this context, the composites reinforced with natural fibers began to be highlighted in the scientific community. However, its utilization is still seen with suspicion due to little or no knowledge of these pr omising materials. Faced with this problem, arose the proposal of this investigative character work, in with it was researched and devel oped a fully recycled composite, of thermoplastic matrix (recycl ed PVC) reinforced with fibers obtained from the bark of green coconut s discarded. For this objective were used various tools of physical, chemical, thermal and mechanical characterization, whose amounts of d eformation fields were obtained by Digital Image Correlation (DIC), c omparing the image of the body not deformed with images of the deforme d body. Finally, we assessed the processes of damage of the composite, through experimental characterization of the evolution of t he isotropic damage by the methods of varying the effective elastic mod ulus (tensile test with loading and unloading) and by Tsai-Wu index wi th the parameters constitutive of hyperbolic tangent function, where the values found, in both methods, were within the expected range for composite, from 0.20 to 0.50.

This thesis focuses on the effect of microstructural variation on the mechanical properties and deformation behavior of ductile iron. To research and determine these effects, two grades of ductile iron, (i) GJS-500-7 and (ii) high silicon GJS-500-14, were cast in a geometry containing several plates with different section thicknesses in order to produce microstructural variation. Microstructural investigations as well as tensile and hardness tests were performed on the casting plates. The results revealed higher ferrite fraction, graphite particle count, and yield strength in the high silicon GJS-500-14 grade compared to the GJS-500-7 grade. To study the relationship between the microstructural variation and tensile behavior on macroscale, tensile stress-strain response was characterized using the Ludwigson equation. The obtained tensile properties were modeled, based on the microstructural characteristics, using multiple linear regression and analysis of variance (ANOVA). The models showed that silicon content, graphite particle count, ferrite fraction, and fraction of porosity are the major contributing factors that influence tensile behavior. The models were entered into a casting process simulation software, and the simulated microstructure and tensile properties were validated using the experimental data. This enabled the opportunity to predict tensile properties of cast components with similar microstructural characteristics. To investigate deformation behavior on micro-scale, a method was developed to quantitatively measure strain in the microstructure, utilizing the digital image correlation (DIC) technique together with in-situ tensile testing. In this method, a pit-etching procedure was developed to generate a random speckle pattern, enabling DIC strain measurement to be conducted in the matrix and the area between the graphite particles. The method was validated by benchmarking the measured yield strength with the material’s standard yield strength. The microstructural deformation behavior under tensile loading was characterized. During elastic deformation, strain mapping revealed a heterogeneous strain distribution in the microstructure, as well as shear bands that formed between graphite particles. The crack was initiated at the stress ranges in which a kink occurred in the tensile curve, indicating the dissipation of energy during both plastic deformation and crack initiation. A large amount of strain localization was measured at the onset of the micro-cracks on the strain maps. The micro-cracks were initiated at local strain levels higher than 2%, suggesting a threshold level of strain required for micro-crack initiation. A continuum Finite Element (FE) model containing a physical length scale was developed to predict strain on the microstructure of ductile iron. The material parameters for this model were calculated by optimization, utilizing the Ramberg-Osgood equation. The predicted strain maps were compared to the strain maps measured by DIC, both qualitatively and quantitatively. To a large extent, the strain maps were in agreement, resulting in the validation of the model on micro-scale. In order to perform a micro-scale characterization of dynamic deformation behavior, local strain distribution on the microstructure was studied by performing in-situ cyclic tests using a scanning electron microscope (SEM). A novel method, based on the focused ion beam (FIB) milling, was developed to generate a speckle pattern on the microstructure of the ferritic ductile iron (GJS-500-14 grade) to enable quantitative DIC strain measurement to be performed. The results showed that the maximum strain concentration occurred in the vicinity of the micro-cracks, particularly ahead of the micro-crack tip. / Denna avhandling fokuserar på effekten av variationer i mikrostrukturen på mekaniska egenskaper och deformationsbeteende hos segjärn. För att undersöka dessa effekter, två olika sorter av segjärn, (i) GJS-500-7 och (ii) högkisellegerad GJS-500-14, gjutits till plattor av olika tjocklekar för att generera mikrostrukturvariationen. Mikrostrukturundersökning, samt drag- och hårdhetsprov gjordes på de gjutna plattorna. Resultaten visade att en högre ferritfraktion, grafitpartikelantal och sträckgräns i den högkisellegerade GJS-500-14-sorten jämfört med GJS-500-7. För att studera förhållandet mellan mikrostrukturell variation och spännings-töjningsbeteendet på makroskala, modellerades detta med hjälp av Ludwigson-ekvationen. De erhållna spännings-töjningsegenskaperna modellerades baserat på mikrostrukturell karaktäristika genom multipel linjärregression och variansanalys (ANOVA). Modellerna visade att kiselhalt, grafitpartikelantal, ferritfraktion och porfraktion var de viktigaste bidragande faktorerna. Modellerna implementerades i ett simuleringsprogram för gjutningsprocessen. Resultatet från simuleringen validerades med hjälp av experimentella data som inte ingick i underlaget för regressionsanalysen. Detta möjliggjorde att prediktera spännings-töjningsbeteendet och dess variation hos gjutna segjärns komponenter med liknande sammansättning och gjutna tjocklekar som användes i denna studie. För att kunna undersöka deformationsbeteendet på mikroskala utvecklades en metod för kvantitativ mätning av töjning i mikrostrukturen, genom DIC-tekniken (digital image correlation) tillsammans med in-situ dragprovning. I denna metod utvecklades en grop-etsningsprocess för att generera ett slumpvis prickmönster, vilket möjliggjorde DIC-töjningsmätning i matrisen och i området mellan grafitpartiklarna med tillräcklig upplösning. Metoden validerades genom benchmarking av den uppmätta sträckgränsen mot materialets makroskopiska sträckgräns mätt med konventionell dragprovning. Det mikrostrukturella deformationsbeteendet under dragbelastning karakteriserades. Under elastisk deformation avslöjade töjningsmönstret en heterogen töjningsfördelning i mikrostrukturen, och bildandet av skjuvband mellan grafitpartiklar. Sprickbildning initierades vid låg spänning och redan vid de spänningsnivåer som ligger vis ”knät” på dragprovningskurvan, vilket indikerar energidissipering genom både begynnande plastisk deformation och sprickbildning. Den lokala töjningen vis sprickinitiering skedde då den lokala töjningen översteg 2%, vilket indikerar att detta skulle kunna vara en tröskelnivå för den töjning som erfordras för initiering av mikro-sprickor. En kontinuum Finita Element (FE) modell utvecklades för att prediktera töjningen hos ett segjärn och dess fördelning i segjärns mikrostruktur. Materialparametrarna för denna modell optimerades genom att anpassa parametrarna i Ramberg-Osgood ekvationen. De predikterade töjningsfördelningarna jämfördes med de experimentell uppmätta töjningsmönstren uppmätta med DIC, både kvalitativt och kvantitativt. Töjningsmönstren överensstämde i stor utsträckning, vilket resulterade i att modellerna kunde anses vara validerade på mikronivå. För att kunna mäta töjningsmönster under dynamiska förlopp på mikronivå utvecklades en metod för att skapa prickmönster och att utföra in-situ CT provning i ett svepeletronmikroskop (SEM). Prickmönstret skapades genom avverkning med en fokuserad jonstråle (FIB), och provades på det ferritiska segjärnet (GJS-500-14 grad). Resultaten visade att maximal töjningskoncentration fanns i närheten av mikrosprickorna, framförallt framför sprickspetsen.

Les matériaux composites 3D obtenus par couture ou piquage transverses présentent de nombreux atouts comparativement aux tissages interlocks ou orthogonaux 3D. Dans le but d’évaluer le potentiel de cette nouvelle génération de matériaux 3D, certaines études ont été consacrées à leur caractérisation mécanique. D’autres études se sont focalisées sur l’influence de certains types de coutures sur la perméabilité de matériaux cousus de type NCF (Non Crimp Fabrics). Cette thèse se propose d’étudier l’apport des coutures de type Tufting dans le renforcement transverse de tissus classiques 2D. Cet apport est évalué, conjointement, du point de vue mécanique et du point de vue de la perméabilité. Parmi les nombreux paramètres de couture, l’étude s’est focalisée sur l’influence de la densité de couture. A ce titre, trois différentes densités de coutures ont été réalisées, grâce à un robot de couture disponible au sein de notre laboratoire. Du point de vue de la perméabilité, les préformes cousues ont été réalisées avec des empilements identiques à ceux des préformes non cousues. L’évaluation des perméabilités a été conduite à travers un banc de mesure de perméabilité à flux unidirectionnel. Avec cette méthode, le tenseur de perméabilité plane est obtenu à travers trois mesures unidirectionnelles : 0° (chaine), 90° (trame) et 45°. L’analyse des résultats montre que la couture de type Tufting induit un effet atténuateur du rapport d’anisotropie K1/K2. D’autre part, il ressort que la position du fil de couture provoque des gradients de perméabilités locaux, très prononcés entre la surface et le cœur de la préforme. Pour les besoins de la caractérisation mécanique, six plaques composites ont été réalisées par le procédé RTM. Pour atteindre les caractéristiques mécaniques hors-plan, des plaques de 20 mm d’épaisseur, cousues et non cousues ont été réalisées. La CIN (Corrélation d’Image Numérique) a été utilisée pour cartographier les distributions des champs de déplacement lors des essais mécaniques (traction, compression sur cube et flexion en poutre courte), ceci afin de tenir compte de la présence des coutures au sein des matériaux. Les performances mécaniques évaluées se sont révélées bien en deçà des attentes, surtout en ce qui concerne les caractéristiques hors-plan. L’analyse micrographique des matériaux a révélé la présence de porosités concentrées au sein, ou dans le voisinage proche, des coutures. D’autre part, les coutures présentaient des courbures ou vrillages, provoquées par le compactage lors de la fermeture du moule RTM.En faisant le lien avec les résultats de perméabilité, il ressort que la présence des porosités au sein des coutures est une conséquence des gradients de perméabilité qui induisent des refermetures de flux d’imprégnation. / 3D composite materials, which obtained by stitching or tufting, have many advantages compared to the 3D orthogonal weaves or interlocks. ln order to evaluate the potential of this new generation of 3D materials, some studies have been devoted to their mechanical properties. Other studies have focused on the influence of certain types of seams on the permeability of materials such as NCF (Non Crimp Fabrics).This thesis is to study the contribution of seams through the thickness of reinforcement 2D classic fabrics. This contribution is evaluated the mechanical properties and their permeability at the same time. Among many stitching parameters, the study focused on the influence of the stitching density. Three different seams densities were carried out through a robot available in our laboratory.ln terms of permeability, the stitched preforms were laminated those of identical unstitched preforms by using Tufting.The evaluation of permeability was conducted in an unsaturated regime through a small scale bench test by the unidirectional flow. With this method, the in-plane permeability tensor is obtained through the measured permeability in three directions : 0° (warp), 90° (weft) and 45°. The results show that the type of Tufting seams reduces the effect of anisotropy ratio Kl/K2. And it is obvious that the position of the stitching thread causes local permeability gradients very pronouncedly between the heart and the surface of the preform. For the purposes of the mechanical properties, six composite plates were made by the RTM process. To achieve mechanical properties through the thickness of the plates of 20 mm thick, stitched and unstitched performed were prepared. DIC (Digital Image Correlation) was used to detect the distribution of displacement fields during mechanical testing (tensile, compression and short bearn bending) in order to take account of the presence of seams within materials. The measured mechanical performance proved below expectations, particularly with regard to the characteristics in the third direction. Micrographie analysis of materials revealed the presence of porosity concentrated within, or near the seams. Moreover, the bends or kinks of seams were caused by compaction during closure of the RTM mold. By connecting with the permeability data, it appears that the presence of porosities in the seams is a consequence ofpermeability gradients that induce impregnation flow reclosing.

This thesis presents work on investigations into the mechanical properties of connective tissue. A model system of hydrogels was used to investigate how volume change through water flow is coupled to relaxation. This was done using digital image correlation (DIC) and a custom built setup. It was found, in hydrogels, that water loss is directly coupled to an increase in tension and water intake is directly coupled to tension relaxation. The experimental setup was tested by investigating the mechanical properties of the well known material polydimethylsiloxane (PDMS) and the novel materials of carbon nanotube (CNT) elastomers, cholesteric liquid crystal elastomers (CLCEs), and 3D polydomain liquid crystal elastomers (3DLCEs). The setup accurately demonstrated the incompressibility of PDMS, even at short time scales, and demonstrated how DIC can map the inhomogeneity of material by locating clusters of CNTs in CNT elastomers by how they deform. Novel results for 3DLCEs were also found, where it was discovered that there is a softening of the bulk modulus at small time scales resulting in a volume increase following deformation, the bulk modulus then recovers and there is over all no volume change. This is in stark contrast to the typical case, where it is the shear modulus that becomes comparable to the bulk modulus, resulting in increased volume. A theoretical investigation was carried out into critical damping in viscoelastic oscillators, where the aim was to apply to the findings to connective tissue. The fractional Maxwell model and zener model where both solved for, where it was found that damping decreases as the material becomes more solid and the peak of critical damping becomes broader. Finally, investigations into how strain relates to the viscoelastic properties of connective tissue were carried out on horse tendon and rat fascia. How relaxation changes was determined through the relaxation constant, where a large constant means it takes the sample longer to relax and it is more solid like. It was found, that in general, the relaxation constant increases quickly with an imposed strain and then either stabilises or increases more slowly. This growth of relaxation constant also occurs during the initial stages of tissue injury, where irreversible deformation occurs.

Magnesium alloys are a popular research topic for structural applications because they have a lower density than conventional structural materials, including steel, titanium, and aluminum; however, the reliability and safety of their mechanical properties must be further proven. An important mechanical property for this purpose is fracture toughness, which is the measure of the material's resistance to crack propagation. In this study, a model of an experiment to investigate the fracture toughness of a magnesium alloy WE43 before and after friction stir processing (FSP) is developed, and the results are compared to those produced by a digital image correlation (DIC) system during an experiment from another paper. The model results of the material before FSP matched well with the DIC results, but the model of the material after FSP only partially matches the DIC results. In addition, a theoretical approach to calculating the standard fracture toughness value, KIc, from the modeling results is proposed, and is found to be a conservative approach.

Road and rail tunnels are important parts of the modern infrastructure. High strength concrete (HSC) is commonly used for tunnels and other civil engineering structures, since it allows high load carrying capacity and long service life. In general, Swedish road and rail tunnels should be designed for a service life of 120 years. However, HSC has shown to be sensitive to severe fires in the moist tunnel environment, i.e., fire spalling may occur. Extensive research shows that addition of polypropylene (PP) fibres in the fresh concrete mix significantly reduces the risk of fire spalling. The durability of a concrete structure is mainly governed by the transport properties. Further, experimental studies aimed at understanding the protective mechanism of PP fibres indicate that fluid transport increases in connection with the melting temperature of such fibres. This might reduce the durability of fire exposed concrete with addition of PP fibres. This study aims to investigate whether the use of PP fibres has any significant effect on the durability of moderate fire exposed concrete structures. The experimental study focused on transport properties related to durability and stiffness reduction of fire exposed civil engineering concrete with and without addition of PP fibres. The study consists of three parts; (i) unilateral fire exposure in accordance with the standard time-temperature curve (Std) and a slow heating curve (SH), (ii) uniformly heating of non-restrained samples to 250oC, and (iii) moderate unilateral fire exposure, 350oC, of restrained samples. Changes in material properties caused by the fire exposure were studied by means of ultrasonic pulse velocity, full field-strain measurements during uniaxial compression core tests, polarization and fluorescence microscopy (PFM), water absorption and non-steady state chloride migration. The study shows that fire exposure influences different properties of importance for load carrying capacity and durability. To get a clear image of the fire damage one has to combine different test methods during damage assessments. Transport properties of concrete both with and without addition of PP fibres were considerably affected even at moderate fire exposure. Hence, the service life might be reduced. All series with addition of PP fibres exhibited higher water absorption compared to the series without PP fibres. The practical importance of this might, however, be small since also the water absorption of concrete without PP fibres was considerably affected for the fire scenarios considered in this study. Behind the fire exposed surface, i.e., between 30 and 60 mm, no change in water absorption was observed for concrete without PP fibres. However, higher water absorption of the series with addition of PP fibres was observed. Indicative fire tests aimed to evaluate the resistance to fire spalling during a subsequent severe fire was also conducted. The concretes with addition of PP fibres showed no signs of fire spalling, while progressive spalling was observed for the concrete without PP fibres. / <p>QC 20150603</p>

Inland waters are important systems for transforming, storing and transporting carbon along the aquatic continuum, but also by emitting carbon dioxide (CO2) and methane (CH4) to the atmosphere. In light of the last decades observed increase in dissolved organic carbon (DOC) in many inland waters across the northern hemisphere, a logical question arise whether other aquatic carbon species display similar trends. This study examined the measured concentrations of dissolved inorganic carbon (DIC) in a boreal catchment over a 14-year period. The objectives were to determine changes in DIC concentration over time and try to explain the causes for the observed changes. Data from 15 mostly forested sub-catchments were analyzed, both over the full time period, and grouped by season. Over the full 14-year period, only two of the sites exhibited significant trends in DIC concentration, both being negative. However, by seasonally grouping the data distinct patterns for the different seasons emerged. The autumn and winter data displayed no significant trends, whereas the spring flood data showed significant negative trends for almost all sites (14 out of 15). The summer data showed significant negative trends for seven sites, and positive for one site. The DIC concentration data were expectedly positively correlated with pH across most sites (13 out of 15). The correlation with DOC was negative for most sites (11 out of 15), possibly indicating different origins of the different carbon species. The DIC concentration was also negatively correlated with discharge for most sites (13 out of 15), suggesting a diluting effect with increased discharge. In conclusion, significant negative trends were observed during the spring flood and summer periods. Although the cause of these trends will require further investigation, the correlation analysis showed that the DIC concentration was closely related to the catchment hydrology. This suggests changes in terrestrial source areas where DIC is mobilized during spring and summer, and that these changes might continue during altered hydrometeorological conditions. The differences in DIC trends between sub-catchments further show the variability of the boreal landscape and highlight the need for local-scale process understanding when scaling to larger landscape units. We further conclude that trends in DIC concentration do not follow observed DOC changes over time, suggesting that DIC and DOC exports are mechanistically decoupled.

Finite element simulation of thermoplastic components is gaining importance as the companies aim to avoid overdesign of the components. Cost of the component can be minimized by using an adequate amount of material for its application. Life of the component, in a particular application, can be predicted as early as during its design phase with the help of computer simulations. To achieve reliable simulation results, an accurate material model which can predict the material behaviour is vital. Most material models consist of a number of material parameters that needs to be fed into them. These material parameters can be identified with the inputs from physical tests. The accuracy of the data extracted from the physical tests, however, remains the base for the aforementioned process. The report deals with the implementation of optical measurement technique such as Digital Image Correlation (DIC) in contrast with the conventional extensometers. A tensile test is conducted on a glass fibre reinforced thermoplastic specimen, according to ISO 527-2/1A, to extract the experimental data with the help of DIC technique. The material behavior is reproduced within a finite element analysis software package LS-DYNA, with the combination of elastoplastic model called *MAT_024 and stress state dependent damage and failure model called GISSMO. The tensile test is performed under quasi-static condition to rule out the strain rate dependency of the thermoplastic material. The mesh sensitivity of the damage model is taken into account with the element size regularization. The thesis concerns setting up a routine for material parameter identification of thermoplastics by full-field calibration (FFC) approach. Also, comparison of the strain field in the specimen, obtained through the newly set up routine against the regular non-FFC i.e. extensometer measurement routine. The major objective being, through the comparisons, a qualitative assessment of the two routines in terms of calibration time vs. gain in simulation accuracy. Material models obtained through both the routines are implemented in three-point and four-point bending simulations. The predicted material behaviors are evaluated against experimental tests.

Les matériaux piézoélectriques et ferroélectriques présentent un comportementélectromécanique couplé. Cette particularité leur a permis d’être utilisés dans de nombreusesapplications telles que les applications de capteur, actionneur, transformateur et récupérateurd’énergie. En outre, en raison de leur comportement non linéaire et dissipatif, les matériauxferroélectriques sont de plus en plus utilisés dans le domaine de l’électronique en tant quecapacité accordable, mémoire non volatile, oscillateur et filtre. La performance et la fiabilitéde ces systèmes dépendent directement des propriétés ferroélectriques et piézoélectriques dumatériau, qui nécessite par conséquent d’être caractérisé. Les propriétés piézoélectriques,ferroélectriques, ferroélastiques et diélectriques des matériaux ferroélectriques ont été le sujetde nombreuses études. Pourtant, les conditions d’essai restent difficiles à maîtriser car lespropriétés thermiques, mécaniques et électriques de ces matériaux sont fortement couplées.Dans cette thèse, un dispositif de mesure de champ de déformation a été conçu pourcaractériser le comportement piézoélectrique et ferroélectrique des céramiquesferroélectriques. Ce dispositif utilise un banc optique ainsi qu’un algorithme de Corrélationd’Images Numériques (CIN) 2D appelé CorreliRT3. Cet algorithme est basé sur une approcheglobale et réduit les erreurs de mesure de déplacement en s’appuyant sur les équationsd’équilibre de la mécanique des solides. Grâce au banc de caractérisation par CIN, il estmontré que les déformations piézoélectriques et ferroélectriques peuvent être mesurées avecune incertitude d’environ 10-5. Cette incertitude est atteinte aussi bien pour des sollicitationssimples que couplées (champ électrique et/ou contrainte mécanique). Il est aussi montré quele banc expérimental permet de vérifier les conditions d’essai en caractérisant l’hétérogénéitédes déformations lors d’un essai matériau.Dans les deux derniers chapitres, un matériau ferroélectrique est caractérisé souschamp électrique et sous contrainte mécanique. Le comportement du matériau est présenté etdiscuté dans les différentes configurations de chargement. Les propriétés matériau, telles queles coefficients piézoélectriques (d33, d31), sont extraites et étudiées en fonction du champélectrique et de la contrainte. Les résultats montrent que la CIN est capable de mesurer etcaractériser le comportement et les propriétés des matériaux ferroélectriques etpiézoélectriques. L’avantage de la CIN étant que, contrairement aux méthodes de mesureclassiques, celle-ci ne perturbe pas les conditions d’essai (mesure sans contact) et permette dedétecter la présence d’erreurs systématiques. / Piezoelectric and ferroelectric materials exhibit a coupled electromechanicalbehaviour. This property allows a use in various kinds of applications such as sensors,actuators, harvesting devices or converters. In addition, due to their non-linear and dissipativebehaviour, ferroelectric materials are increasingly used in electronic applications such astunable capacitors, non-volatile memory, oscillators and filters. The performance andreliability of such devices depend on the material electromechanical properties, whichconsequently need to be characterised. In the past decades, such characterisation was largelydeveloped and the piezoelectric, ferroelectric, ferroelastic and dielectric properties offerroelectrics were the subject of numerous studies. Yet the test conditions are difficult tocontrol due to the strong interplay between thermal, mechanical and dielectric properties.In this work, a full-field measurement apparatus has been designed to characterise thepiezoelectric and ferroelectric strain behaviour of ferroelectric ceramics. This apparatus usesan optical setup and a 2D Digital Image Correlation (DIC) algorithm named CorreliRT3. Thealgorithm is based on a global approach and reduces the displacement field errors using thebalance equations of solid mechanics. It is shown that piezoelectric and ferroelectric strainscan be measured with an uncertainty around 10-5 by using the developed setup. Thisuncertainty is reached under uncoupled or coupled loading (electric field and/or stress). It isalso shown that the experimental setup can control the test conditions by characterising thestrain heterogeneity during the test.In the two last chapters, a ferroelectric material is characterised under electric field andstress. The material behaviour is presented and discussed in the different loadingconfigurations. Material properties, such as the longitudinal and transverse piezoelectriccoefficients (d33, d31) are extracted and analysed as a function of the electric field and stress.The results show that the DIC technique is able to measure and characterise the behaviour andthe properties of ferroelectric and piezoelectric materials. The main benefits of this techniqueis that, contrary to classical measurement techniques, the measurement does not alter the testconditions. Moreover, DIC is able to detect test anomalies such as strain heterogeneities

Mes travaux de thèse consistent à proposer et valider une démarche de métrologie 3D in-situ multi-capteurs/multi-échelles. L'intégration de systèmes de mesure au sein du moyen de production permet d'être très réactif aux présences de défauts géométriques et ainsi directement proposer des actions correctives. Afin de limiter les arrêts de fabrication, donc la diminution de l'efficience de la machine-outil, l’interopérabilité entre la fabrication et la mesure doit être maximisée : il est important de proposer une phase de mesure rapide et assurant une qualité minimum des données acquises. Un outil de mesure par caméras (Stéréo-corrélation d'images) est proposé dans ces travaux. Basé sur la connaissance du modèle FAO de la pièce et de l’environnement de travail, cet outil de mesure permet d'obtenir une cartographie des écarts géométriques de la pièce directement dans le repère FAO. Ainsi, il est possible d'analyser directement les données de mesure dans le même repère que celui de la fabrication : les temps de traitements des données sont réduits. / Integrating inspection procedures in the machining process contributes to process optimization. The use of in-situ measurement allows a betterreactivity for corrective actions. However, to be highly efficient, Machining and Inspection Process Planning must reach a high level of integration. It is hereessential to focus on the compromise measurement time vs precision: the time dedicated to inspection must be limited, but not to the detriment ofmeasurement quality. A measurement process for in-situ machining defect detection is proposed based on a stereo-DIC.